Although it would make the time hiding from depth charges more entertaining considering the cargo. Das Blow
/colombian drug lords did the sensible—and trendy—thing: they spent 4,000 million pesos (approx $2.2 million) to build their own drug-trafficktacular submersible.
I seem to recall a cheaper version of a submarine being available during my childhood...and I'm sure it was completely legit.
(first pic via REUTERS/Jaime Saldarriaga, second from here)